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491.
针对浓度大、色度高的印染废水难以处理的情况,选用加入光纤的光催化体系进行研究。采用溶胶凝胶法制备了Ag+/TiO2粉体光催化剂,用固体紫外可见光谱、X射线衍射对其进行表征。选用亚甲基蓝溶液作为目标降解物,评价了Ag+/TiO2在可见光下的光催化活性。分别考察了加入石英芯侧光光纤与塑料侧光光纤反应体系下,催化剂量、光纤数量、光照强度和pH值等因素对亚甲基蓝降解实验的影响。结果表明,选用20 mg/L的亚甲基蓝,采用催化剂量为11.67 g/L,500根侧光光纤,300 W的外部光源,pH值约为11时,光催化降解效果最佳,均能达到90%以上。 相似文献
492.
固态碳源去除地下水硝酸盐的模拟实验 总被引:3,自引:0,他引:3
选取了5种研究较少的固体材料,棉花、丝瓜络、甘蔗渣、可降解餐盒、木屑作为去除地下水硝酸盐的外加碳源。在锥形瓶中进行反硝化对比实验,研究了不同固态碳源下NO3--N、NO2--N、NH4+-N及pH的变化情况,分析了NO3--N及总氮的去除率。研究结果表明,反硝化过程中pH呈升高趋势,在6.9~8.5范围内浮动。可降解餐盒和丝瓜络相对于其他的固态碳源来说,对NO3--N和总氮有较高的去除率,但丝瓜络的总氮去除率明显低于可降解餐盒。可降解餐盒的硝酸盐去除率达到98.28%,总氮去除率达到93.48%。可降解餐盒能够有效地去除地下水硝酸盐,达到以废治废的效果,是经济有效的最佳固态碳源。 相似文献
493.
微生物制剂与玄武岩纤维联用处理城市废水 总被引:1,自引:0,他引:1
为了探索一种新型的去除水体中有机物的工艺,以模拟城市废水为研究对象,研究不同工况条件下,复合微生物制剂、组合双环玄武岩纤维填料以及复合微生物制剂与组合双环玄武岩纤维填料结合对模拟城市废水中COD的去除情况。实验结果表明,复合微生物制剂与组合双环玄武岩纤维填料结合在曝气的情况下对COD的去除能力较高。在复合微生物制剂与组合双环玄武岩纤维填料结合的条件下,对COD浓度为500 mg/L左右的模拟城市废水的去除效率可达 97.22%;影响模拟城市废水中COD去除效果的各因素的主次顺序依次为反应时间>曝气时间>投加量=pH;得出最佳工况参数是:复合微生物制剂的投加量为0.05 g/L,曝气时间为72 h,反应时间为96 h,pH为7。 相似文献
494.
调理剂对堆肥产品重金属生物有效性的影响 总被引:1,自引:0,他引:1
城市污泥中重金属含量及其生物有效性是限制污泥农用的主要因素,因此,研究污泥堆肥化处理过程中重金属生物有效性,对污泥的农用具有重要意义。实验以城市污泥为原料,以菌菇渣和秸秆为调理剂,设置4个处理:A(污泥∶菌菇渣∶秸秆=1∶0.4∶0.025)、B(污泥∶菌菇渣∶秸秆=1∶0.3∶0.025)、C(污泥∶秸秆=1∶0.12)和D(污泥∶秸秆=1∶0.09),进行好氧堆肥实验,采用BCR顺序提取法测定各种形态的重金属,研究堆肥前后重金属形态的变化规律。结果表明,城市污泥中Cu、Ni、Pb和Cr主要以可氧化态及残渣态存在,生物有效性较低,而Zn和Cd主要以酸溶态和可还原态存在,生物有效性较高;堆肥过程显著降低了Cu、Zn、Ni和Pb的生物有效性,并改变了Cu、Zn、Ni、Pb、Cr和Cd的形态分布,使污泥中的Cu、Zn、Ni、Pb和Cd向着更稳定的可氧化态或残渣态转变;污泥经过堆肥处理后,Cu、Zn和Ni 3种重金属生物有效性关系为:ABCD,与其他处理相比,处理A残渣态的Pb和Cr增加比例较多,综合来看,处理A对重金属生物有效性的降低最为明显,重金属钝化效果最佳。 相似文献
495.
Li Yuan Jinjin Cheng Qian Chu Xiu Ji Jianjun Yuan Fayun Feng 《Journal of environmental science and health. Part. B》2013,48(8):693-701
The bioconcentration and elimination of racemic benalaxyl (BX) in trout liver microsomes and in juvenile rainbow trout (Oncorhynchus mykiss) were investigated to determine whether the fish can bioconcentrate and degrade this fungicide enantioselectively. Both enantiomers of BX were extracted with organic solvents and evaluated using high-performance liquid chromatography. In the microsomes, BX degradation followed first-order kinetics, and the S?(+) enantiomer of BX was eliminated twice as rapidly as the R?(?) enantiomer, resulting in residues enriched for R?(?)?BX. In vivo experiment, chiral analysis showed an obvious selective bioconcentration of BX based on statistically altered enantiomer fractions (EFs) in the fish compared with the values in the water. The R?(?)?BX was initially preferentially bioconcentrated by rainbow trout and then dissipated more slowly than its antipode. The mean half-lives for individual enantiomers were calculated as 31.6 h for R?(?)?BX and 20.3 h for the S?(+)?form. The results of the study showed that the degradation of BX enantiomers was stereoselective in rainbow trout. 相似文献
496.
Phung DT Connell D Miller G Hodge M Patel R Cheng R Abeyewardene M Chu C 《Chemosphere》2012,87(4):294-300
Chlorpyrifos is the most common organophosphate insecticide registered for use in Vietnam and is widely used in agriculture, particularly rice farming. However, chlorpyrifos exposure to and adverse effects on farmers has not been evaluated. In this study, biological monitoring of chlorpyrifos exposure in a group of rice farmers was conducted after a typical application event using back-pack spraying.Urine samples (24 h) were collected from the rice farmers before and post insecticide application. Samples were analysed for 3,5,6-trichloropyridinol (TCP), the major urinary metabolite of chlorpyrifos, using an enzymatic pre-treatment before extraction followed by HPLC-MS/MS. Absorbed Daily Dose (ADD) of chlorpyrifos for farmers were then estimated from urinary TCP levels, expressed as μg g−1 creatinine. The analytical method for urinary TCP had a low detection limit (0.6 μg L−1), acceptable recovery values (80-114%), and low relative percentage differences in duplicate and repeated samples.Post-application chlorpyrifos ADD of farmers varied from 0.4 to 94.2 μg kg−1 (body weight) d−1 with a mean of 19.4 μg kg−1 d−1 which was approximately 80-fold higher than the mean baseline exposure level (0.24 μg kg−1 d−1). Hazard Quotients (ratio of the mean ADD for rice farmers to acute oral reference dose) calculated using acute oral reference doses recommended by United States and Australian agencies varied from 2.1 (Australian NRA), 4.2 (US EPA) to 6.9 (ATSDR).Biological monitoring using HPLC-MS/MS analysis of urinary TCP (24 h) was found to be an effective method for measuring chlorpyrifos exposure among farmers. This case study found that Vietnamese rice farmers had relatively high exposures to chlorpyrifos after application, which were likely to have adverse health effects. 相似文献
497.
Yinghui Mo Liping Sun Lu Zhang Jianxin Li Jixiang Li Xiuru Chu Liang Wang 《Frontiers of Environmental Science & Engineering》2023,17(4):49
498.
Paul Chiou Wei Tang Che-Jen Lin Hsing-Wei Chu T. C. Ho 《Environmental Modeling and Assessment》2009,14(3):333-350
Speciated samples of PM2.5 were collected at a site in Jefferson County, Texas by US EPA (Environmental Protection Agency) from July of 2003 to August
of 2005. A total of 269 samples with 52 species were measured; however, 22 species were excluded in this study because of
too many below-detection-limit data. The data set was analyzed by positive matrix factorization (PMF) to infer the sources
of PM observed at the site. The analysis identified ten sources: sulfate-rich secondary aerosol I (35.9%), sulfate-rich secondary
aerosol II (21.0%), cement/carbon-rich (11.7%), wood smoke (8.8%), metal processing (6.3%), motor vehicle/road dust (5.7%),
nitrate-rich secondary aerosol (3.3%), soil (3.2%), sea salt (2.6%), and chloride depleted marine aerosol (1.6%). Sulfate
and nitrate mainly exist as salts. The two sulfate-rich secondary aerosols account for almost 57% of the PM2.5 mass concentration. The factor containing highest concentrations of Cl and Na was attributed to sea salt due to the proximity
of the monitoring site to the Gulf of Mexico. The chloride depleted marine aerosol was related to the sea salt aerosol. Cement/carbon-rich,
wood smoke, metal processing, and motor vehicle/road dust factor were likely to be the local sources. 相似文献
499.
Using a hybrid approach to optimize experimental network design for aquifer parameter identification
Liang-Cheng Chang Hone-Jay Chu Yu-Pin Lin Yu-Wen Chen 《Environmental monitoring and assessment》2010,164(1-4):133-142
The main objective of this study is to evaluate the land-use change and its relationship with its driving factors in the loess hilly region. In this study, a case study was carried out in Pengyang County. We set two land-use demand scenarios (a baseline scenario (scenario 1) and a real land-use requirement scenario (scenario 2)) during year 2001–2005 via assuming the effect of driving factors on land-use change keeps stable from 1993 to 2005. Two simulated land-use patterns of 2005 are therefore achieved accordingly by use of the conversion of land use and its effects model at small regional extent. Kappa analyses are conducted to compare each simulated land-use pattern with the reality. Results show that (1) the associated kappa values were decreased from 0.83 in 1993–2000 to 0.27 (in scenario 1) and 0.23 (in scenario 2) in 2001–2005 and (2) forest and grassland were the land-use types with highest commission errors, which implies that conversion of both the land-use types mentioned above is the main determinant of change of kappa values. Our study indicates the land-use change was driven by the synthetic multiply factors including natural and social–economic factors (e.g., slope, aspect, elevation, distance to road, soil types, and population dense) in 1993–2000 until “Grain for Green Project” was implemented and has become the dominant factor in 2001–2005. 相似文献
500.
Tomonori Ishigaki Chu Van Chung Nguyen Nhu Sang Michihiko Ike Koji Otsuka Masato Yamada Yuzo Inoue 《Journal of Material Cycles and Waste Management》2008,10(2):165-172
A methodology for estimating the methane emissions from waste landfills in Hanoi, Vietnam, as part of a case study on Asian
cities, was derived based on a survey of documents and statistics related to waste management, interviews with persons in
charge, and field investigations at landfill sites. The waste management system in Hanoi was analyzed to evaluate the methane
emissions from waste landfill sites. The quantity of waste deposited into the landfill was evaluated from an investigation
of the waste stream. The composition of municipal waste was surveyed in several districts in the Hanoi city area, and the
quantities of degradable organic waste that had been deposited into landfill for the past 15 years were estimated. Field surveys
on methane emissions from landfills of different ages (0.5, 2, and 8 years) were conducted and their methane emissions were
estimated to be 120, 22.5, and 4.38 ml/min/m2, respectively. The first-order reaction rate of methane generation was obtained as 0.51/year. Methane emissions from waste
landfills were calculated by a first-order decay model using this emission factor and the amount of landfilled degradable
waste. The estimates of methane emissions using the model accorded well with the estimates of the field survey. These results
revealed that methane emissions from waste landfills estimated by regional-specific and precise information on the waste stream
are essential for accurately determining the behavior of methane emissions from waste landfills in the past, present, and
future. 相似文献